A resurgent Asian nation has just elevated hawkish nationalists to the pinnacle of power. Its maritime conflicts with neighbours raise the risk of military confrontation along key corridors of world trade. Memories of past national greatness infuse officials with a determination to compete for regional leadership. The country’s re-emergence could rewrite the geopolitical map of Asia.

No, it’s not China. Japan is set to surprise the world and change its region if it can reverse the economic decline that has led many to write off its influence.

It’s true that Prime Minister Shinzo Abe, sworn in on Wednesday, confronts problems that make those of other leaders look mild by comparison. Japan has one of the oldest populations on earth, the effects of the tsunami and nuclear crisis of 2011 linger, its politics have been plagued by gridlock, and it is subject to growing challenges from a confident China.

Some Americans, viewing China as Asia’s future and Japan as its past, consider the alliance with Tokyo as anachronistic—or even a liability in a transformed world. But it would be a mistake to write off Japan as a friend. It remains America’s strongest ally in Asia, with world-class capabilities that make it a serious player in the global balance of power.

Tokyo has worked creatively to forge new strategic relationships that could reshape its region. The emerging debate over national identity will drive the country’s evolution from pacifism towards a more assertive regional posture.

Surprisingly, the basis of Japan’s resilience is its economy. It was the original Asian tiger, growing for several decades at rates comparable to China’s today. China may have surpassed Japan in gross domestic product (GDP) by harnessing the productive power of 1.3 billion citizens, yet it’s worth remembering that Japan produces a similar level of output with less than one-tenth the population. For all its economic troubles, Japan retains pockets of technological excellence that could drive future growth.

Tokyo has translated that economic might into foreign policy activity. One of the world’s top foreign aid donors, Japan has pledged $5 billion to help rebuild Iraq and another $7 billion for Afghanistan, where it is the largest donor after America. It has taken the lead in helping Burma reconstruct infrastructure and human resources frayed by decades of neglect. It offers bases and generous host-nation support to nearly 50,000 US forces who serve as a linchpin of security in East Asia.

Japan has also built up its military power. It often goes unacknowledged, but the country boasts a technologically sophisticated military capable of working closely with American forces across a range of missions. Japan spends more on defence than all but four countries; its navy is the most capable of any US ally and it possesses superior missile defences. Its qualitative military capabilities surpass those of China in several areas.

In a breakout from long-standing restraints, Japan is increasingly wielding that military power. In the last decade, the country has refuelled warships in the Indian Ocean to support the war in Afghanistan, deployed troops to Iraq, participated in the tsunami recovery mission in Indonesia, sent officers to police a ceasefire in Nepal, exercised with the Indian, Australian, Korean, and American navies, participated in the UN stabilization mission in Haiti, and dispatched naval vessels off Somalia for anti-piracy operations.

Japan has also lifted restrictions on arms exports that were holding back its domestic arms industry and expanded military capacity-building in South-east Asia. Tokyo has secured military agreements with Australia and India and formed a triangular strategic partnership with Washington and New Delhi.

These developments reflect the fierce domestic debate that is churning beneath the surface in Japanese politics about Japan’s future security doctrine. This was catalysed by China’s explosive rise and aggressive tactics towards its neighbours. The election of Abe and the strength of new nationalist formations like the Japan Restoration Party reflect a rightward shift in the country’s political landscape that could have far-reaching consequences for America’s leadership in the face of China’s challenge.

As Washington undertakes a strategic rebalance towards Asia, it will need all the friends it can get. Few countries have been better allies than Japan. America’s hopes will be bound up in the decisions of Japan’s new government to get its economy on track, fashion a strategic foreign policy, and sort out its politics. If Japanese power was the problem of Asia before 1945, in the 21st century Japanese strength can serve as part of the solution.

THE WALL STREET JOURNAL

Richard Fontaine and Dan Twining are, respectively, the president of the Center for a New American Security and senior fellow for Asia at the German Marshall Fund of the US.